[BBSA-DBN][HSO 4 ]: a novel –SO 3 H functionalized Bronsted acidic ionic liquid for easy access of quinoxalines

A novel –SO3H difunctionalized Bronsted acidic ionic liquid (BAIL) 1, 5-bis (butanesulphonic acid)-diazobicyclo [4,3,0] non-5-enium hydrogen sulphate [BBSA-DBN][HSO4] is introduced for efficient synthesis of quinoxalines via condensation of substituted 1,2-diketones and various aromatic 1,2-diamines. It could serve as a dual functional catalyst for these reactions. This method has the advantages of mild reaction conditions, high yields, short reaction times, easy work-up, non-chromatographic separations and being environmentally friendly. This protocol provides an effective and environmentally friendly alternative methodology for production of quinoxalines and extends the chemical utilization of benzil in organic synthesis. This room-temperature-derived ionic liquid is highly acidic due to presence of two –SO3H groups and two HSO4− anions. Moreover, the IL [BBSA-DBN][HSO4] could be easily recovered and reused at least five times without change in its catalytic activity. The formation of IL [BBSA-DBN][HSO4] was confirmed by 1H, 13C NMR spectroscopic techniques.